title: Heat shock protein 70 inhibits the activity of Influenza A virus ribonucleoprotein and blocks the replication of virus in vitro and in vivo.
abstract: BACKGROUND
  Heat shock protein 70 (Hsp70) was identified as a cellular interaction partner of the influenza virus ribonucleoprotein (RNP) complex. The biological significance of the interaction between Hsp70 and RNP has not been fully investigated.
  
  
  RESULTS
  Here we demonstrated that Hsp70 was involved in the regulation of influenza A viral transcription and replication. It was found that Hsp70 was associated with viral RNP by directly interacting with the PB1 and PB2 subunits, and the ATPase domain of Hsp70 was required for the association. Immunofluorescence analysis showed that Hsp70 was translocated from the cytoplasm into the nucleus in infected cells. Then we found that Hsp70 negatively regulated the expression of viral proteins in infected cells. Real-time PCR analysis revealed that the transcription and replication of all eight viral segments were significantly reduced in Hsp70 overexpressed cells and greatly increased as Hsp70 was knocked down by RNA interference. Luciferase assay showed that overexpression of Hsp70 could inhibit the viral RNP activity on both vRNA and cRNA promoters. Biochemical analysis demonstrated that Hsp70 interfered with the integrity of RNP. Furthermore, delivered Hsp70 could inhibit the replication of influenza A virus in mice.
  
  
  CONCLUSIONS
  Our study indicated that Hsp70 interacted with PB1 and PB2 of RNP and could interfere with the integrity of RNP and block the virus replication in vitro and in vivo possibly through disrupting the binding of viral polymerase with viral RNA.
authors.affiliation: Center for Molecular Immunology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, P. R. China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Junjie
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Tong
authors.forename: Wenjun
authors.initials: W
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Ye
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004285:Dogs; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D005260:Female; D016679:Genome, Viral; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D009980:Influenza A virus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000494:pharmacology; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology; D014162:Transfection; D014779:Virus Replication / Q000187:drug effects / Q000235:genetics / Q000502:physiology*
chemical_list: D018840:HSP70 Heat-Shock Proteins; D034741:RNA, Small Interfering; D012367:RNA, Viral; D012261:Ribonucleoproteins; D012321:DNA-Directed RNA Polymerases